Pixel circuitry and driving method thereof

1. Field of the Invention

The present invention relates to a pixel circuitry and a driving method thereof, and more particularly, to a circuitry that utilizes the characteristic of the storage element to change the polarity of a pixel signal stored in the storage element.

2. Description of Related Art

FIG. 1 is a diagram of a conventional pixel cell. Referring to FIG. 1, the pixel cell 100 includes a transistor T1, a storage capacitor Csc and a liquid crystal layer Clc. It is assumed that the transistor T1 has a gate, a drain and a source respectively connected to a scan line, a data line and a pixel electrode Pi. When the transistor T1 is conducted, in the meanwhile, the pixel electrode Pi is connected to the data line and receives a corresponding pixel signal through the data line for charging the pixel electrode Pi to a proper voltage. Next, the transistor T1 is turned off and the electric charge corresponding to the pixel signal is stored in the storage capacitor Csc for controlling the rotation of the liquid crystal and the light transmission corresponding to pixel cell 100.

As known, polarity inversion is an important concept for driving the liquid crystal. An inversed electric field is provided to the liquid crystal into different frame periods for eliminating the DC residue of the liquid crystal. For this reason, an external frame buffer is often needed to increase the frame rate for executing the polarity inversion and for avoiding flickers. However, an additional cost will be increased.

Accordingly, the present invention provides a pixel circuitry for a display apparatus and a driving method thereof that utilizes the characteristic of the storage element to change the polarity of the pixel signal stored in the storage element during a frame time. Therefore, the present invention can achieve the function of frame buffer and increase the frame rate by once writing data to the pixel circuitry.

A pixel circuitry for a display apparatus is provided in the present invention. The pixel circuitry includes a storage element, a scan switch, a first control circuit and a second control circuit. The scan switch delivers a pixel signal to the storage element in response to a scan signal during a frame period and the storage element stores the pixel signal. The first control circuit selectively provides a reference voltage to one of the first terminal and the second terminal of the storage element. The second control circuit selectively connects a pixel electrode to one of the first terminal and the second terminal of the storage element.

According to an embodiment of the foregoing pixel circuitry, the first control circuit includes a first switch and a second switch. The first switch is coupled between the first terminal of the storage element and the reference voltage. The second switch is coupled between the second terminal of the storage element and the reference voltage.

According to an embodiment of the foregoing pixel circuitry, the second control circuit includes a first switch and a second switch. The first switch is coupled between the first terminal of the storage element and the pixel electrode. The second switch is coupled between the second terminal of the storage element and the pixel electrode.

The driving method for a pixel circuitry is provided in the present invention, wherein the pixel circuitry has a storage element. First, a pixel signal is delivered to the storage element in response to a scan signal during a frame period. A reference voltage is selectively provided to one of the first terminal and the second terminal of the storage element. Besides, a pixel electrode is selectively connected to one of the first terminal and the second terminal of the storage element.

According to an embodiment of the foregoing driving method, the reference voltage is provided to the first terminal of the storage element and the pixel electrode is connected to the second terminal of the storage element while in a first polarity. Besides, the reference voltage is provided to the second terminal of the storage element and the pixel electrode is connected to the first terminal of the storage element while in a second polarity.

The present invention provides a pixel circuitry and a driving method that can change the polarity of the pixel signal stored in the storage element during a frame period. Since the storage element can keep the voltage offset between its two terminals invariable, the polarity of the pixel signal stored in the storage element can be changed by selectively providing the reference voltage to one of the first terminal and the second terminal of the storage element during the frame period. Then, the pixel signal stored in the storage element is transmitted to the pixel electrode. The pixel circuitry can achieve the function of frame buffer and increase the frame rate, which can display the pixel signal with different polarities during one frame period.

In order to make the features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.

It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

FIG. 1 is a diagram of a conventional pixel cell.

FIG. 2 is a diagram of the pixel circuitry according to an embodiment of the present invention.

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Previous Patent Application:
Liquid crystal display device and method for driving same
Next Patent Application:
Potential generation circuit and liquid crystal display device
Industry Class:
Computer graphics processing, operator interface processing, and selective visual display systems

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